Hair loss can be induced by various causes, for example, reduced metabolic activity of hair roots, reduced physiological activity of the scalp, local disorders of blood circulation which result from a decrease in the amount of blood flowing through the peripheral blood vessels of the subcutaneous tissues of the head, nutritional deficiencies, stress, side effects of drugs, and hereditary factors. For example, the probability of hair loss is greater in people with the gene associated with hair loss. However, age, stress, environmental factors and the like are more closely involved in hair loss. Although hair loss is induced by the above-mentioned causes, little known about the exact causes of hair loss.
Currently commercially available hair growth stimulants and hair growers include vasodilators, e.g., capronium chloride, minoxidil (Rogaine®) and various extracts, hormonal drugs, e.g., estrogen and estradiol, for suppressing the activity of male hormones, and male hormone inhibitors, e.g., pentadecanoic acid and finasteride. The hormonal drugs for suppressing the activity of male hormones and the male hormone inhibitors are clinically ineffective and cause adverse effects, such as erectile dysfunction. Various kinds of drugs, such as Propecia®, tricomin, spironolactone, cyproterone acetate, Nizoral®, cimetidine and oral contraceptive pills, have been introduced into the market, but their effects have proved to be unsatisfactory.
In recent years, drugs for treating and preventing alopecia have been developed and marketed. For example, FDA-approved Rogaine® (minoxidil) and Proscar® (finasteride) for oral administration, which is a drug inhibiting the activity of 5-α-reductase and the subsequent production of dihydrotestosterone, are currently sold as hair growth stimulants. However, these hair growth stimulants are very expensive and are ineffective when applied directly to the scalp. The drugs are limited in their use because of unexpected side effects upon oral administration. Further, hair growth stimulant compositions containing various extracts have been used, such as extracts from many plants including labiatae and asteracease. However, these compositions suffer from the problem of skin trouble upon application on the skin.
Thus, there is a need for regenerative compositions, such as those that stimulate hair growth or prevent hair loss and offer convenience in use without severe adverse effects, such as skin irritation, and erectile dysfunction.